What’s Happening Beneath The Surface: Saving the Nassau Grouper

The Nassau grouper has suffered a steep decline in its regional populations due to overfishing, especially at its spawning sites. In this article, we outline this grouper’s status, and highlight the hope for its recovery through science, policy, and community efforts. With ongoing research and local action throughout the Caribbean, there’s still a chance to help this iconic reef fish bounce back from decline. 

The Rise, Fall, and Hope for the Nassau Grouper

Once thriving across the Caribbean, the Nassau grouper (Epinephelus striatus) was a top predator on coral reefs and a vital species for local fisheries. Over 3.5 million pounds of Nassau grouper were captured in Cuba’s commercial fishery in one year (1964), but have steadily declined since then. These fish gather in large groups to migrate to spawning sites during the winter months—a behavior that  still makes them easy targets today. Unregulated fishing, especially at these spawning sites, caused sharp population declines in the US Caribbean in the 1980s decade. Once-abundant and numerous aggregations dwindled, and the species is now designated as  critically endangered throughout much of the region.

Protecting What’s Left

To avoid the risks of the Nassau grouper’s extinction in the future, the US National Oceanic and Atmospheric Administration (NOAA) Fisheries listed it as a “threatened species” under the Endangered Species Act in 2016. Furthermore in 2024, the U.S. government designated over 2,300 square kilometers of critical habitat across Florida, Puerto Rico, and the U.S. Virgin Islands. Regulations had already banned killing any Nassau grouper year-round  in the US Caribbean federal waters (1991), then it was further prohibited in local waters of Puerto Rico (2004) and in the USVI (2006). Regional collaborations among Caribbean nations, some with closed seasons and others with year-round no-take marine reserves, aim to protect spawning adults and support population recovery across borders.

Science and Conservation in Action

While signs of recovery are limited, ongoing research and monitoring provide hope throughout the region. Surveys in coral reef habitats (such as NOAA’s National Coral Reef Monitoring Program, NCRMP) are showing that Nassau groupers still occur at low densities in Puerto Rico and the USVI, but may be increasing more recently. There have been additional efforts by researchers to track their movements, study their spawning behaviors, and protect essential habitats. One such success story is the occurrence of spawning aggregations off Puerto Rico’s west coast—a signal that some protections throughout the US Caribbean may be aiding the recovery.

Isla Mar: Leading Local Recovery Efforts

In Puerto Rico, Isla Mar, in collaboration with local and federal agencies, is playing a vital role in Nassau grouper conservation. Since 2012, their team and other local scientists have led monitoring of fish spawning aggregations, documented spawning sites, and mapped essential habitats for juvenile stages. Their work combines local ecological knowledge, underwater surveys and new technologies like passive acoustic monitoring, underwater video techniques and acoustic tagging to understand the grouper’s behavior. By partnering with fishers, researchers, conservationists and government agencies, Isla Mar not only gathers data to guide policies but also builds community support for the recovery of this iconic species.